Helmholtz resonator detonation attenuation means for internal combustion engines



Aug. 28, 1956 A. e. BODINE, JR 2,750,474 HELMHOLTZ RESONATOR DETONATIONATTENUATION MEANS FOR INTERNAL COMBUSTION ENGINES Original Filed Ju1y'2,1951 INVEN TOR.

4413.527 fiop/Ms, Jk. BY

United States Patent HELMHOLTZ RESONATOR DETONATION ATTEN- gA'ION MEANSFOR INTERNAL COMBUSTION N INES Albert G. Bodine, In, Van Nuys, Calif.

Original application July 2, 1951, Serial No. 234,688, now

Patent No. 2,573,536, dated October 30, 1951. Divided and applicationOctober 24, 1951, Serial No. 252,818, now Patent No. 2,738,781, datedMarch 20, 1956. Divided and application December 6, 1955, Serial No.551,263. Again divided and this application April 16, 1956, Serial No.578,475

1 Claim. (Cl. 123-191) This invention relates generally to internalcombustion engines and t0 means for suppressing irregular burning anddetonation of fuel-air mixture therein. The invention is based on mydiscovery that detonation in combustion engines involves acoust cphenomena and can be alleviated by means of certain acoustic apparatusused in combination with the combustion chamber.

The present application is a division of -my copending applicationSerial No. 551,263, filed December 6, 1955, allowed February 15, 1956,entitled Piston Carried Detonation Suppression Means for InternalCombustion Engines. That parent application was in turn a division of myapplication Serial No. 252,818, filed October 24, 1951, entitled EngineDetonation Control by Acoustic Methods and Apparatus, now Patent No.2,738,781, which application was a division of my earlier applicationSerial No. 234,688, filed July 2, 1951, entitled Engine DetonationControl by Acoustic Methods and Apparatus, now Patent No. 2,573,536.

The present invention is based on the fact that detonation in an enginecombustion chamber produces sound waves, a large part of which rise tohigh amplitude at resonant frequencies of the chamber, and on mydiscovery that the sound waves produce the various wellknown and harmfulmanifestations of detonation. According to my basic invention, I inhibitor attenuate these harmful efiects by interfering with or attenuatingthe high amplitude detonation-induced sound waves, and this is done byuse in connection with the combustion chamber of acoustic attenuationmeans made responsive to the frequencies at which the detonation inducedsound waves build up to high amplitudes.

The object of the present invention is the provision of an especiallysimple and effective acoustic attenuator means for the combustionchamber of an internal combustion engine, adapted for piston mounting,having the ice advantage of ease of incorporation in the piston, and lowcost.

The invention will best be understood from the following detaileddescription of an illustrative embodiment thereof, reference for thispurpose being had to the accompanying drawing showing a verticaltransverse section through an internal combustion engine, the sectionpassing medially through the piston and piston mounted attenuators.

With reference to the drawing there is shown an illustrative L-headengine comprised of water-cooled block 10, watercooled head 11, piston12 working in cylinder 13 in head 10, exhaust valve 16, and spark plug17.

An intake valve, not shown, will be understood to be located alongsideexhaust valve 16, out of the plane of the drawing. Head 11 has an innercombustion chamber wall 20, enclosing a combustion chamber space 21 overthe cylinder and valves, as shown. A plurality of Helmholtz resonators24 are incorporated in the head wall of the piston. Each resonator isformed by a bore 25 extending upwardly through the head wall of thepiston merely to the top surface thereof, and by a smaller bore 26extending from bore 25 through the top surface of the piston, the latterforming the neck of the resonator. The bottom of bore 25 is then closedby a plug 27, which may be secured in place by peening, as indicated at28. Helmholtz resonators whose necks communicate with the combustionchamber are thus formed in the head wallof the piston by a very simpleand inexpensive operation, lending itself readily to incorporation inconventional piston structures.

The attenuation of detonation in internal combustion engines by use ofHelmholtz resonators tuned to be resonant to detonation frequencies hasbeen fully explained in my aforementioned Patent No. 2,573,536, and neednot be repeated herein.

It will be understood that the drawings and description are merelyillustrative of one specific embodiment of the invention, and thatvarious changes in design, structure and arrangement may be made withoutdeparting from p No references cited.

